Then can't he stop evil without interfering with our free will, and imput any lessons or appreciation we may gain from it into us, using his omnipotence?
If he can't, then God can't do everything.
If he can, then why won't he?
Well, your question is fair enough. Where do I start?
First of all, yes, God is all-powerful. He can do anything. We may not understand what He is doing at all times, but who are we to judge anyway? We are far below His level of intelligence and understanding, more than we could ever imagine. We weren't there when He created the earth. We weren't there when He suffered and then came back to life. We weren't there when He performed miracles. What do we know anyway? Who are we to judge God's plan? He knows what He's doing. All we can do is trust Him and do what He says, which will actually help fight evil anyway.
Now, God gave us free will. We can choose to believe Him, or lie to ourselves and others in an attempt to replace Him for our own evil desires. We have the choice. If there was no evil, we wouldn't have anything to choose but God, and that wouldn't even be a choice.
Think of the evil and suffering like this. Imagine a bear trapped in a bear trap. A hunter comes along. Out of compassion, he decides to let the bear go free. When he tries to let the bear out, however, it won't let him near. It doesn't understand that the hunter is actually just trying to help. The hunter knows that if the bear continues to reject his help for too long, it will die. He is forced to shoot the bear with tranquilizer darts. This way, it will fall asleep so that he can help without resistance. The bear thinks, however, that the hunter is trying to harm it. What the bear doesn't realize is that if it stopped resisting, the hunter wouldn't need to tranquilize it, and although the darts are painful, it is worth the suffering for the end result.
God is the compassionate hunter, and we are the bear. We get ourselves into trouble, but reject God, thus making our problem worse. God helps us, however. We may see it as suffering, but the end result will be worth it. We need to stop pretending that we know everything, that we have all the answers. We need to humble ourselves, trust God, and bear the pain for the sake of the end result. Again, who are we to judge? What have you done lately to prevent some amount of evil or suffering? Not nearly as much as God! Who are you to judge Him, when you don't even practice what you preach? Besides, He has a plan. Trust Him and obey Him, and you will like the end results.
Now, this is a very deep subject I'm about to get into. You said that if God can't make both at once, He is not all-powerful. Well, God created our ability to think, our way of thinking, and the concepts of right, wrong, good, evil, free will, and choice. God could make things so that these concepts didn't exist. Now, no one but He could imagine or understand how this is possible. We can understand if we think deeply, however, that there could be a state of existence without these concepts. Again, we are not intelligent enough beings to imagine what it would actually be like, but God could do it. Why doesn't He? Well, He made things the way He did for a reason. We don't, nor could we ever, understand why, but He has His reasons. All that He wants from us is to trust Him and do what He says.
In conclusion, yes, He is all-powerful, and He could make a world both with free will and without evil, but so many other things would have to change. He wants things the way they are, otherwise He would have done things like that. I hope I have been helpful. Ask me if you have any further questions. God bless you!
